This invention relates to the field of phased array antennae, and more particularly, this invention relates to phased array antennae using an array lattice formed from a plurality of subarray lattices.
Low cost phased arrays are required on naval ships, land based radar stations and similar areas. Traditional phased arrays using periodic lattices and transmit/receive modules are prohibitive in cost. When the antenna are designed for use with short wavelengths, the transmit/receive modules are bulky and cannot be positioned between antenna elements. Also, advanced radar designs require low side lobe architecture. Also, many subarrays are desired.
One prior art approach uses a traditional periodic array orientation of subarrays. It has been found that this type of prior art phased array antenna produces grating lobes. This is found especially true at higher frequency applications, such as the X-band and KU-band. Even lower frequency applications than the UHF, L-band and S-band have been found to produce grating lobes.
It would also be advantageous if any phased array antenna at these higher applications that are formed from different array lattices of subarray lattices could use a low cost circuit board in lieu of individual modules with lower cost antenna elements. Antenna elements possibly could be printed radiating elements or surface mounted components. Not only could ship board phased arrays be used, but also space-based systems, ground-based SATCOM nodes, cell towers and wireless internet could be applicable and used with an improved phased array antenna.
Some prior art proposals have used different antenna designs, such as U.S. Pat. No. 4,052,723 that shows a randomly agglomerated subarray for phased array radars. This has not been found advantageous.
The present invention advantageously provides a phased array antenna having a plurality of subarray lattices arranged in an aperiodic array lattice. Each subarray lattice comprises a plurality of antenna elements arranged in an aperiodic configuration such that any transmitted or received signals have reduced side lobes. In one aspect of the invention, each subarray lattice includes a circuit board and a plurality of antenna elements arranged in an aperiodic configuration on the circuit board. Electronic circuitry is supported by the circuit board and operatively connected to the antenna elements for amplifying, phase shifting and beam forming any transmitted or received signals with reduced side lobes. Because of the aperiodic configuration, the electronic circuitry can be mounted between antenna elements. An antenna support member can support each circuit board and the plurality of subarray lattices as an aperiodic array lattice.
In yet another aspect of the present invention, each antenna element is arranged in an aperiodic configuration and spaced from each other a distance greater than one-half wavelength of a transmitted or received signal. The plurality of subarray lattices that form the aperiodic array lattice are formed as concentric circles in an aperiodic configuration. The antenna elements of each subarray lattice are configured in a spiral. Each subarray lattice is substantially identical to each other. The number of subarray lattices arranged in the aperiodic array are the same as the number of antenna elements forming each subarray lattice. The antenna elements can comprise surface mounted antenna elements or printed antenna elements.
In yet another aspect of the present invention, the circuit board is formed as a multilayer circuit board with amplifiers, phase shifters, beam forming networks, and central networks distributed among the layers. The multilayer circuit board can be formed of green tape in yet another aspect of the present invention.